Randall, this is so true. I was on a 2 1/2 week dive trip to Indonesia in November and continuing my 4x weekly HIIT (high intensity interval training) classes on return along with Tai Chi and Yin yoga weekly. In January a strange pain in my right leg, hip and back appeared and gradually worsened. Dr. had x-ray and cortisone shot in SI joint which seemed to help for 3 days when the left side just really hit me. The upshot is slipped SI-L5 joint with near excruciating pain and surgery on June 2 involving a lumbar 'cage', screwed in plate to stabilize the SI joints, a back brace and 6-9 months of rehab. Dr. says I probably can even get back to diving, though, despite my age. He said I seemed to be in otherwise excellent health
We must never take good health for granted whether it's systemic, structural or mental.